We’re rewarding the question askers & reputations are being recalculated! Read more.

Hot answers tagged

16

EPIC (PDF) is a Cassegrain type reflector telescope so there's the fixed hyperbolic secondary mirror in the middle of the telescopes light path / focal plane. While that could be removed during post-processing and combining multiple exposures focusing at slightly different angles of the telescope itself (or shifting of the sensor on the focal plane, depends ...


13

Halo orbits and their cousins Lissajous orbits (like the one DSCOVR is in) around the Sun-Earth L1 and L2 have periods of about a half-year. They are not generally stable and they want to "unwind" along what's called an unstable manifold. In this question I link to Roberts 2002, The SOHO Mission L1 Halo Orbit Recovery From the Attitude Control Anomalies of ...


8

In this view, EPIC sees the Sun rise in the west, and the Sun set in the east, at least 13 times a day. This is incorrect. This statement is based on the planned activity of sending home at least 12 images a day. Communication link restrictions and the higher priority of the scientific instruments on DSCOVR over EPIC means that this does not always happen. ...


7

TLEs are (as far as I know) only issued for Earth-orbiting spacecraft. Since DSCOVR is placed in L1 and not in a near-Earth orbit that's probably why its TLE are missing. I checked for TLEs of SOHO and ACE, which are also placed in L1, and SatCat gives the same output. P.S: The fact that there's no TLEs does not mean that the spacecraft is not tracked. TLEs ...


6

On June 27th, 2019 NASA states that DSCOVR is in a "safe-hold". All DSCOVR space weather instrument data and other instrument data have been suspended as the spacecraft has entered into safe-hold. Anomaly investigations and associated recovery activities are underway. Source: NASA A few days later they said it had to do with the satellite's position. ...


6

Part of the news release you link to (under the image) has the information you're looking for: Once the instrument begins regular data acquisition, new images will be available every day, 12 to 36 hours after they are acquired by EPIC. These images will be posted to a dedicated web page by September [2015]. I'll update with links and more ...


6

The report 'Resurrected DSCOVR Propulsion System – Challenges and Lessons Learned' contains a schematic of the propulsion system: and indicates thruster locations: thruster 9 and 10 are on the bottom: The thrusters were used as follows: ... the DSCOVR propulsion system, which utilizes ten 4.5 N thrusters in blowdown mode to perform Midcourse ...


6

The orbit's probably close to perpendicular to the Earth-Sun line, since its imaging target is the Earth. The reason the angles referenced are all positive is because they measure the divergence of two lines, Earth-Sun (passing through SEL-1) and Earth-spacecraft. In essence, they're describing the distance from SEL-1, always a positive value, in terms of ...


5

In your embedded YouTube video, at 1m 16s EPIC's Lead Scientist Jay Herman says, "Epic takes at least one set of images about every two hours." If Epic takes a set of images every 1h 50m 46.153s, it will take 13 sets of images in 24 hours, each showing a sunrise and a sunset.


5

@TildalWave mentioned DSCOVR was originally Triana built around the SMEX-Lite bus. I think the key is that Triana originally had all its cells, but DSCOVR does not. I believe, as @RussellBorogove commented, the original solar array has been replaced with an upgrade. The cells have been left off to save weight, cost and heat dissipation. SMEX-Lite, when ...


4

In this case, the terms are being used interchangeably. DISCOVR has one type of engine, i.e. the MOOG Monarc 5N thruster. DSCOVR is equipped with ten thrusters that can be used for spacecraft attitude control as well as translational maneuvers that are required for mid-course corrections and orbital adjustment maneuvers around L1. Ten thrusters are fed ...


3

You can now see the Lissajous path of DSCOVR using the Blueturn app: http://app.blueturn.earth Just zoom out (a lot) from the default EPIC view... More generally, this app interpolates EPIC images received from DSCOVR using real-time 3D projection techniques. In such this is the first and only interactive video of the Whole Earth, with 2+ year of data. ...


2

I've accepted the great answer by @Leorex. I went back and found that the video has closed captions (the little [CC] thing) and indeed my original transcription was wrong. EDIT: and then I looked at the whole thing again six months later, after this answer and decided that no, the problem is more than just confusing "sunset" for "sun set". @DavidHammon's ...


2

Actually as part of my application Blueturn (http://app.blueturn.earth) which makes interpolated video feed out of EPIC images, I have been following the EPIC feed a lot and I observed that except the memorable Moon transit of July 5th 2016, we don't have other images of the Moon photobombing the Earth. There is a reason for this; the presence of the Moon ...


2

I can't say for sure, I but would guess that it's due to maneuvers. There are other satellites in Libration Point Orbits that maneuver on the 2-3 week time frame. (They do so no matter what, it's not on an as-needed basis) Also there are a couple of factors associated with maneuvers that can preclude the ability to 'do science' on the spacecraft: The ...


2

An additional factor resulting in small (and even single pixel) glints is that the horizontally oriented ice crystals may cover only a small region. For example an ice cloud may be small, or ice crystals in the rest of a large cloud may be oriented randomly (as opposed to horizontally) as they tumble through the air.


1

I think this was answered perfectly well in both the answer and the comment left by Tildal. So it would appear as an overexposed region, that might appear as pretty much anything after post-processing, including the Moiré fringed dot with typical read and blue channel interference pattern around it on the image that you noticed, once the RGB sources, or ...


1

This may be less confusing: The camera shot includes either the sunrise terminator in the west or the sunset terminator in the east, at least 13 times per Earth solar day.


1

I realize this is an old question, but in case someone stumbles across it (as I just did): It is true that TLEs for 2015-007B = DSCOVR booster are not provided by Space-Track. However, that object (and others in high Earth orbits) are occasional annoyances for the astronomers looking for near-earth asteroids, and they've imaged 2015-007B many times over ...


1

I suggest you take a look at my answer here: https://space.stackexchange.com/a/23743/21677 I made an app that interpolates EPIC images on a 3D globe, and also displays DSCOVR and its path at any time in the past 2 years since DSCOVR started its service. It's a web app, or a mobile app (Android+iOS) if you open this link from your phone or ablet. It's free ...


Only top voted, non community-wiki answers of a minimum length are eligible